Tertius
Your HTML, converted.
Paste your HTML. See exactly how it will land in an inbox. Fix what breaks. Copy it out formatted. Free, no account, nothing leaves your browser.
How to use it
- Paste your HTML into the left panel. The preview updates as you type.
- Read the report. It flags what breaks in real email clients, what Gmail will clip, and which links and images are wrong.
- Click Inline the CSS. Most email clients throw away your style block. This rewrites every rule as an inline style attribute so it survives.
- Check both previews. Mobile width and dark mode catch most of what desktop light mode hides. Images off shows what a reader sees before they click "display images."
- Select & Copy, then paste into Gmail, Outlook, Apple Mail, or any editor that accepts formatted text.
Tertius runs entirely in your browser. Your HTML is never uploaded, never stored, and never seen by us.
Ctrl+A then Ctrl+C on Windows. Cmd+A then Cmd+C on Mac.
Built on a working farm
Moon Tree Farm raises goats and makes soap in Keystone Heights, Florida. Two sisters, Erin and Kira, run it. Erin’s husband Dustin builds the software. Every tool here began as something this family needed — this one included — and was used on the farm before it was offered to anyone else. The tools pay for the hay.
Also built here: Herbie · Teen Tab · Moon Tree Institute · Grand Testimony · Art Biz Project · MyNextVote
See the farm →